Effects of recombinant murine interferon-gamma on pregnant mice and their fetuses

Recombinant murine interferon-gamma (Rec-MuIFN-gamma) was administered intramuscularly to C3H/HeNCrj mice on Days 6-15 of gestation at dosage levels of 8 X 10(5), 4 X 10(6), and 2 X 10(7) u/kg/day. Dams were killed for examination of fetuses on Day 18 of gestation. Pregnant females that received 2 X 10(7) u/kg/day of Rec-MuIFN-gamma showed uterine bleeding on Days 10-15 of gestation and could not maintain their pregnancy. These dams died on Days 13-17 or were killed in extremis on Days 10-15 for examination, and therefore no fetal data were available for this group. In the 2 X 10(7) u/kg/day group, the mean absolute weights of the lung and spleen increased and the mean absolute weight of the liver, red blood cells (RBC), hematocrit, and hemoglobin decreased significantly. Surviving dams in the 8 X 10(5) and 4 X 10(6) u/kg/day groups showed significant increases in the mean absolute weights of the lung, liver, kidneys, and spleen and a decrease in platelet count. Significant increases in the weights of the heart and ovaries and decreases in RBC, hematocrit, and hemoglobin were observed in the 4 X 10(6) u/kg/day group. Histopathological examination revealed increased extramedullary hematopoiesis in the spleen of the 4 X 10(6) and 2 X 10(7) u/kg/day groups. Fetuses showed no external, visceral, or skeletal malformations and variations caused by the administration of Rec-MuIFN-gamma in any of the treated groups.(ABSTRACT TRUNCATED AT 250 WORDS)